Sorption of Se(IV) on Fe- and Al-modified bentonite

The sorption behavior of Se(IV) on Fe- and Al-modified bentonite is studied through batch experiments. In order to introduce active centers for Se(IV) sorption, bentonite was modified with iron, iron oxocations and aluminum oxocations at 400, 600 and 800 deg C. It was found that calcined temperature had great effect on the sorption with above 80 % sorption at 400 deg C, whereas with only 5 % sorption at 800 deg C. The sorption capacities for Se(IV) were 112.5 mg/g by FeOH-B, 60.1 mg/g by AlOH-B and 71.9 mg/g by Fe-B, respectively. The pH-dependent and ionic strength-independent Se(IV) sorption on these modified bentonites demonstrated that the sorption mechanism of Se(IV) was inner-sphere surface complexation at low pH values. (author)